1. Field of Invention
The invention relates to an ink-jet recording apparatus and a method of manufacturing the same.
2. Description of Related Art
An ink-jet type recording apparatus is known and typically used for recording image data outputted from a personal computer, a facsimile machine, and the like. This type of recording apparatus is superior to other types of recording apparatus in that it is quiet and capable of recording on sheets of various materials.
U.S. Pat. No. 5,402,159 discloses a piezoelectric element formed by stacking a plurality of layers of piezoelectric material. Each layer is sandwiched by a pair of opposed electrodes and is polarized in the opposing direction of the pair of opposed electrodes. The structure is produced by lamination with the various layers pressed while applying heat thereto. Then external negative electrodes and external positive electrodes are bound to the electrode leads. After which the laminate is immersed in an oil bath filled with an oil, such as silicon oil, heated to about 130xc2x0 C. and an electric field is applied between the external negative electrodes and the external positive electrodes to provide polarization. Following that, the piezoelectric element is then assembled within a channel body and an orifice plate to provide the ejector array.
U.S. Pat. No. 5,266,964 discloses a print head having a similarly constructed piezoelectric element. The piezoelectric element is made up of a plurality of layers each of which has mounted on an upper surface of alternating negative and positive electrodes. The negative electrodes are positioned above partitions of a channel structure when assembled to provide the piezoelectric print head. The positive electrodes are positioned above what will be the ink channels. Outside polarizing electrodes are then placed on both the top and bottom surfaces and the laminate is placed within an insulating oil, such as silicon oil, again at a temperature of about 130xc2x0 C. and an electric field is passed by the outside polarizing electrodes. Thus, the piezoelectric element is polarized. The laminated piezoelectric element is then removed from the oil, the outside polarizing electrodes are removed, and the piezoelectric element then assembled to a channel block and nozzle plate to produce the print head.
Thus, in both of the disclosed methods, the laminated piezoelectric elements are polarized before they are assembled with the cavity plate, that is, the channel body or block having the ink channels, and connected to an electric circuit. Such a procedure is difficult and cumbersome involving a number of steps to obtain the piezoelectric element. Further, polarized conditions of the piezoelectric elements may be affected by the steps performed following the polarizing step.
The invention provides an ink-jet printing apparatus having improved polarized piezoelectric elements and a method of manufacturing the same.
According to an aspect of the invention, an ink-jet printing apparatus is manufactured by stacking a plurality of plates to form a cavity plate that has a plurality of nozzles and a plurality of cavities communicating with their respective nozzles, and by forming an piezoelectric actuator that has a plurality of piezoelectric elements, each of which is sandwiched by a pair of opposed electrodes. Then, the piezoelectric actuator is fixed to the cavity plate such that the plurality of piezoelectric elements face their respective cavities. A flexible cable is connected to each pair of opposed electrodes. Thereafter, each piezoelectric element is polarized in an opposing direction of each pair of opposed electrodes by applying a first voltage by a first power source to each piezoelectric element through the flexible cable and by applying a second voltage different from the first voltage by a second power source to each piezoelectric element through the flexible cable.